19 November 2013

Active volcano discovered under Antarctica ice sheet

Mount Sidley is the youngest volcano rising above the ice in West Antarctica's Executive Committee Range. A group of seismologists has detected new volcanic activity under the ice about 30 miles ahead of Mount Sidley. (Doug Wiens)
Researchers from the Washington University in St. Louis have discovered a volcano located beneath roughly one kilometer of ice in western Antarctica, and they believe that the heat it produces could increase the rate of ice loss from one of the region’s primary ice streams.

In January 2010, a team of investigators, led by professor of earth and planetary science Doug Wiens, established two crossing lines of seismographs across Marie Byrd Land. It marked the first time that scientists deployed multiple instruments in the interior of Antarctica capable of operating throughout the entire year, even in the coldest regions of the continent, the university said in a statement.

The seismograph operates like a massive CT machine, using disturbances created by far-off earthquakes to develop images of the ice and rock deep below the surface. The goal, according to Wiens, was to weigh the ice sheet in order to help recreate the climate history of West Antarctica.

However, to do so, he and his colleagues “had to know how the earth’s mantle would respond to an ice burden, and that depended on whether it was hot and fluid or cool and viscous,” the university said in a statement. “The seismic data would allow them to map the mantle’s properties In the meantime, automated-event-detection software was put to work to comb the data for anything unusual.”

Between January 2010 and March 2011, the machines discovered two bursts of seismic events. Washington University doctoral student Amanda Lough analyzed the data more closely in order to determine whether the cause was two slabs of rock grinding on one-another, ice groaning over another sheet of ice, or even hot gases and liquid rock erupting through a volcanic complex.

Lough, Wiens and their team continued studying the phenomenon, and eventually became convinced that they had stumbled upon a new volcano that was forming deep below the ice. The discovery of the volcano was announced Sunday in the advanced online issue of the journal Nature Geoscience.

According to Larry O’Hanlon of Discovery News, the earthquakes the scientists observed serve as “a possible hint that an eruption is on the way to open the flood gates for water and ice pouring out of that vast region.” He added that any such eruption would probably happen under 4,600 feet of ice, and would be likely to reach the surface.

Nonetheless, he added, “that wouldn’t stop all that hot rock from melting a lot of ice and drastically increasing the melt water draining from under this gigantic basin. All that liquid water under the ice could also lubricate ice streams so they flow faster. If that was to happen, it would be a new and unwelcome addition to the worrisome problem of polar ice losses from global warming that’s already measurably raising sea levels worldwide.”

The researchers also located a plume of volcanic ash buried in the ice using radar data, O’Hanlon said. That ash is believed to have originated from Mount Waesche, located in the southern end of the Executive Committee Range in Marie Byrd Land. Based on the speed of ice accumulation in the region, the ash is believed to have descended on the ice surface approximately 8,000 years ago. Currently, Mount Waesche is believed to be dormant.

“Most mountains in Antarctica are not volcanic, but most in this area are,” Wiens said. “Is it because East and West Antarctica are slowly rifting apart? We don’t know exactly. But we think there is probably a hot spot in the mantle here producing magma far beneath the surface.”

Is there danger of the new volcano erupting? “Definitely,” Lough said. “In fact because of the radar shows a mountain beneath the ice I think it has erupted in the past, before the rumblings we recorded.”

The research was funded by the US National Science Foundation (NSF) Division of Polar Programs.

Now read: Earth acts as a giant particle accelerator, creating the dangerous Van Allen radiation belts


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